bash: setenv: command not found?

I have to install a package on my computer. To make that package working, an environment variable must be added to the system. So, I tried the following command line:
/*******************************************************/
[root@localhost ref17-09-04]# setenv ZIPPER_PACK /mnt/winE/Programs/mesh/ref17-09-04/zipper-1.14/
bash: setenv: command not found
[root@localhost ref17-09-04]#
/*******************************************************/
I tried that command in many folders (/root/, …) but in vain.
I can't understand why my system doesn't find even the help exists!!!
In fact:
/*******************************************************/
[root@localhost ref17-09-04]# man setenv
returns me the entire help...
/*******************************************************/

My OS is Linux Fedora Core 1.

The same problem is faced with these commands too: environ, getenv, putenv, …

Please help me to make that commands working.

Thanks…

setenv is not a command, but a c-shell built-in function,
i don't know if bash also uses it.
in BOURNE sh: XXX=abc; export XXX; do-thejob
in KORN sh: export XXX=abd; do-thejob
in C-sh (the best on commando line) setenv XXX abc; do-thejob
the best way works in bourne, korn, bash and cron:
env XXX=abc do-thejob